3.5. Index Files

When a table is stored on
disk, it is often referred to as a file. In this
case, each row of the table is referred to as a
record and
each column is referred to as a field. (These
terms are often used for any table.)

Since disk access is typically slow, an important goal is to reduce
the amount of disk accesses necessary to retrieve the desired data
from a file. Sequential searching of the data, record-by-record, to
find the desired information may require a large number of disk
accesses, and is very inefficient.